Meta-xenyl phosphoric acid derivatives



Patented May 17, 1938 UNITED STATES META-XENYL PHOSPHORIC ACID DERIVA- TIVES Edgar C. Britten and Shailer L. Bass, Midland,

Mich assignors to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application January 6, 1936, Serial No. 57,783

15 Claims.

This invention concerns certain new organoderivatives of phosphoric acid and meta-phenylphenol. The characteristic diphenyl, or phenylphenyl, group, CsH5.CuH4-. as well as the phenyl-phenoxy group, CuH5CoHi-O, which are present in these compounds, are also known as the xenyl and xenoxy" groups, respectively, which latter terms we prefer to use in this application to avoid confusion of nomenclature. Said new compounds have the general formula.

wherein Y and Z each represent halogen or an aryloxy group. The invention, then, consists in the group of new compounds comprising metaxenyl phosphoric acid halides and triaryl-phosphatcs containing from one to three meta-xenyl roups.

The mixed triaryl-phosphates having the above general formula are prepared by reacting a phosphorus oxyhallde successively with metaxenol or an alkali salt thereof and at least one other phenolic compound, 0. g. phenol, alkyl phenol, halo-phenol, naphthol, guaiacol, paraxenol, ortho-xenol, etc., or the alkali metal salts thereof. The order in which the different phenolic compounds are reacted is immaterial, although we find it convenient first to react the phosphorus oxy-halide with the proportion of meta-xenol necessary to form a meta-xenyl phosphoric acid dihalide, or a di-lmeta-xenyl) phosphoric acid monohalide, as desired, and thereafter to react such acid halide with a different phenolic compound to form the desired mixed triaryl-phosphate product... Trimeta-xenyl) phosphate is prepared by reacting sutficient meta-xenol with a phosphorus oxyhalide to form the desired product.

The above reactions are carried out by heating a mixture of the appropriate materials to a reaction temperature, preferably in the presence of a reaction catalyst such as metallic cal- The temin any particular case upon the reactants employed, the relative proportions thereof, the presence or absence of a catalyst, etc. Since, however, the reaction is accompanied by an evolu- 'tion of hydrogen halide when the phenols themselves are used, it is usually sufficient merely to heat the reaction mixture to a temperature at which hydrogen halide is evolved. The reactions are preferably carried out at the lowest conven ient reaction temperature, usually below 200 0., since at higher temperatures by-product formation may occur to an objectionable extent.

In forming a mixed triaryl-phosphate the intermediate meta-xenyl phosphoric acid halide products may be separated as such, e. g. by fractionally distilling the reaction mixtures in which they are formed. However, we findlit convenient, after formation of such intermediate acid halide, to add the desired quantity of a second phenolic compound, e. g. phenol, to the crude reaction mixture and to continue the reaction to form the triaryl-phosphate product before attempting any purification. By operating in such manner, the extra steps involved in separating the intermediate acid halide product are avoided.

Following completion of the heating step in the preparation of the trlaryl-phosphates, air is preferably bubbled through the hot reaction mixture to remove hydrogen halide and other volatile impurities therefrom. The mixture is then fractionally distilled to separate the triaryl-phosphate product.

The following equations showing the preparation of (l) a mcta-xenyl phosphoric acid dihalide, 2) a dimeta-xenyl) phosphoric acid monohalide, 3) din1eta-xenyll-phenyl phosphate, and 4) trimeta-xenyl) phosphate are illustrative of the type of reactions involved in operating according to the procedure described above:

and 1120 grants of higher boiling In the above equations X represents halogen.

Example 1 A mixture of 340 grams 2 moles) of pure metaxcnol and 1381 grams 9 moles) of phosphorus oxyehloride was heated to a temperature between '72 and 103 C. for about 88 hours, i. e. until hydrogen chloride was no longer evolved from the mixture. The latter was then fractionally distilled, first at atmospheric pressure until the unreacted phosphorus oxychloride had been removed, and thereafter under vacuum. There was obtained 1033 grams 6.75 moles) of unreacted phosphorus oxychloride, 396 grams 11.38 moles) of meta-xcnyl phosphoric acid dichloride, materials. ltieta-xcnyl phosphoric acid dichloride is a colorless liquid, boiling at approximately 218-221 C. at 9 to 11 millimeters pressure, and having a specific gravity of 1.358 at 25 C./4 C., the formula being:

Example 2 A mixture of 510 grams (3 moles) of metaxcnol, 155 grams 1.01 moles) of phosphorus oxychloride, and 5 grams (0.05 moles) of anhydrous magnesium chloride was heated with stirring at temperatures gradually increasing from 95 to 1 5 C. for 6.5 hours. Hydrogen chloride and other volatile impurities were then blown out of the reacted mixture with air and said mixture was dissolved in 700 grams of orthodichlorobenzene. The resultant solution was washed successively with a dilute hydrochloric acid solution, a dilute aqueous sodium hydroxide solution, and water. It was then tractionally distilled under vacuum, whereby 4'73 grams (0.85 mole) of a trimeta-xenyl phosphate product was separated. Tri-meta-xenyl phosphate is vcry'soluble in alcoho], benzene, coal tar hydrocarbons, chlorinated hydrocarbons, and other lacquer solvents. It is a white crystalline solid melting at 84-86 C.,

boiling at approximately 384 C. at 10 millimeters pressure, and having,' the formula;

1 O O-Uo-t-oOUnrx i) ii (4) a O-Oon+rox, o-fi-o Example 3 A mixture of 143.5 grams (0.5 mole) of metaxenyl phosphoric acid dichloride, grams (1.06 moles) of phenol, and 1 gram of anhydrous magnesium chloride was heated with agitation to a temperature between 96 and C. for 4.75 hours. The reacted mixture was blown with air to remove hydrogen chloride and other volatile impurities dissolved, in 300 grams of orthodichlorobenzene, and washed successively with dilute hydrochloric acid, dilute aqueous sodium hydroxide solution, and water. The resulting solution was then fractionally distilled under vacuum, yielding 81.4 grams (0.2 mole) of a meta-xenyl-di-phenyl phosphate product. This compound is a colorless viscous liquid, boiling at 293 C. at 8 millimeters pressure, having a specific gravity of 1.202 at 60/4 C., andthe formula;

Example 4 A mixture or 105.5 grams (0.5 mole) of phenyl phosphoric acid dichloride, grams (1.03 moles) of rneta-xenol, and 1 gram of anhydrous magnesium chloride was heated with stirring at temperatures gradually increasing from 101 to 156 C. for 5.25 hours. Hydrogen chloride and other volatile impurities were then removed by blowing the mixture with air. The reacted mixture was dissolved in 250 grams of orthodichlorobenzene and the resultant solution washed successivcly with dilute hydrochloric acid, dilute aqueous sodium hydroxide solution, and water. This solution was fraetionally.dlstilled under vacuum, whereby 05.8 grams (0.14 mole) of a phenyl dimeta-xenyl phosphate product was separated. Said compound is a highly viscous liquid, having a boiling point of approximately 345 C. at 8 millimeters pressure, a specific gravity of 1.203 at 60/4 0., and the formula;

Example 5 90.5 grams (0.315 mole) of meta-xenyl phosphoric acid dichloride, 70.7 grams (0.655 mole) of ortho-cresol, and 1 gram of anhydrous magnesium chloride were reacted together at a temperature between 88 and 159 C. for 4.75 hours. Hydrogen chloride and other volatile impurities were then removed from the reaction mixture by blowing with air and the mixture was dissolved in 150 grams of orthodichlorobcnzene, washed successively with dilute hydrochloric acid, dilute aqueous sodium hydroxide solution, and water. and fractionally distilled under vacuum. 95.8 grams (0.223 mole) of di-ortho-cresyl metaxcnyl phosphate was thereby obtained as a viscous liquid having a specific gravity of 1.172 at 6074 C., a boiling point of 284 to 298, C. at 5 millimeters pressure, and the formula;

Example 6 grams (0.63 mole) of meta-xenol, and 1.0 gram of anhydrous magnesium chloride was heated at a temperature of 102" to 156 C. for 7.75 hours.

Hydrochloric acid gas and other volatile impurities were then vaporized out of the heated mixture with air. The reaction mixture was dissolved in 400 cubic centimeters of carbon tetrachloride and successively washed with dilute hydrochloric acid, dilute aqueous sodium hydroxide, and water. The resulting solution was then decolorized with animal charcoal and frac tionally distilled to remove the carbon tetrachloride whereby 150.4 grams (0.269 mole) of a dimeta-xenyl para-cyclohexyl phenyl phosphate product was obtained as a residue. This product is a light brown, viscous liquid having a refractive index of 1.6002 at the specific gravity 1.165 at 60/4 C., and probably the formula;

grams (9.27 moles) Hf unreacted phosphorous oxychloride was separated. The residue, consisting of 705.4 grains of a beta-naphthyl phosphoric acid di-chloride product, was used in the preparation of the mixed naphthyl-metaxenyl phosphates. v

A mixture of 235 grams of the above betanaphthyl phosphoric acid di-chloride product containing approximately 82 per cent of the pure diihalide, 265 grains (1.56 moles) of metaxenol, and 1 gram of'magncsium chloride was heated with agitation at temperatures gradually increasing from 77 to 160 C. for 8.1 hours. The reaction mixture was dissolved in 1 kilogram of carbon tetrachloride and washed successively with dilute aqueous hydrochloric acid, dilute aqueous sodium hydroxide, and water. The resulting solution was then decolorized with animal charcoal and iractionally distilled to remove the carbon tetrachloride whereby 376 grams of a di- (mela-xenyl)-bcta-naphthyl phosphate product was obtained as a residue. This product is a red highly viscous oil having a refractive index of 1.6395 at the specific gravity 1.213 at (NP/4 C., and probably thoformula;

In a similar manner a meta-xenyl phosphoric acid di-halide may be reacted with another phenolic compound, 0. g. cresol, etc., to form mixed acid halides such asnicta-xcnyi-cresyl phosphoric acid mono-halide. This compound in turn may be further reacted with an additional phenolic compound. 0. g. phenol, ctc.,'to form mixed triaryl-phosphate compounds such as (meta-xenyl)-cresyl-plienyl-phosphate in which the substituting aryl groups all differ one from the other.

Instead of employing phosphorus oxychloride as a reactant inpreparing our products, we may employ phosphorus oxybromide, in which case our intermediate meta-xenyl-phosphoric acid halides are the bromides. For instance, phos phorus oxybromide may be reacted with 1 or 2 moles of meta-xenol to form meta-xcnyl phosphoric acid dibromide and di-imeta-xenyllphosphoric acid monobromide respectively. Either of these acid bromides may be reacted with any other phenolic compound or its salts, e. g. cresol, sodium tcrtiarybutyl-phenolat-e, etc., to form a triaryl-phosphate of the present class. The procedure involved in carrying out such reactions is similar to that hcreinbeforc described.

Our meta-xenyl phosphoric acid halides and triaryl-phosphate products containing the metaxenyl group are, for the most part, viscous liquids or low melting solids. They are insoluble in water, soluble in most organic solvents, odorless, unailectcd by light, and resistant to hydrolysis and oxidation. Upon prolonged heating with sodium hydroxide they break down to yield ortho-phosphoric acid and phenolic derivatives comprising meta-xenol. The acid halides are useful a intermediates for the preparation of a wide variety of organo-phosphates containing the mcta-xonoxy pdical e. g. mixed trlarylphosphates of the present class, etc. The new triaryl-phosphatcs herein disclosed are substantially non-flammable and are useful as plasticizers, fire-proofing agents, etc., incellulose acetate and nitro-eellulose compositions, varnishes,

wherein Y and Z each represent a member of the group consisting of halogen and aryloxy groups, the step which consists in reacting a phosphorus oxyhalide with a compound selected from the class consisting of meta-xenol and alkali metal salts thereof.

2. In a method of preparing an organo-derivative of phosphoric acid having the general formula:

wherein Y and Z each represent a member of the group consisting oi halogen and aryloxy groups. the step which consists in heating phosphorus oxychloride to a reaction temperature with incta-xenol in the presence of a catalyst selected irom the class consisting of the chlorides of the metals magnesium, aluminum, and iron.

3. in a method of making a compound having the general formula:

wherein X represents halogen, the step which consists in heating a phosphorus oxyhalide to a reaction temperature with approximately a molecular equivalent of a compound selected from the class consisting of meta-xenol and alkali metal salts thereof.

4. In a method of making meta-xcnyl phosphoric acid dichloride, the step which consists in heating phosphorus oxyehloride to a reaction temperature with approximately a molecular equivalent of mcta-xcnol.

5. In a method of making a triaryl-phosphate having the general formula:

I U ()R wherein R and R represent aromatic hydrocarbon radicals, the steps which consist in heating a phosphorus oxyhalide to a reaction temperature with not more than twice its molecular equivalent of a compound selected from the class consisting of meta-xenol and alkali metal salts thereof, to form a meta-xenyl phosphoric acid halide, and heating the latter to a reaction temperature with another phenolic compound to form a mixed triaryl-phosphate.

6. 1h a method of making a triaryl-phosphate having the general formula:

wherein R and R represent aromatic hydrocarbon radicals, the step which consists in heating a meta-xenyi phosphoric acid halide to a reaction temperature with another phenolic compound to form a mixed triaryl-phosphate.

'7. In a method of making a triaryl-phosphate having the general formula:

wherein R and R represent aromatic hydrocarbon radicals, the step which consists in heating an aryl phosphoric acid halide to a reaction temperature with meta-xenol to form a mixed triaryl-phosphate. I

8. In a method of making tri-meta-xenyl phosphate, the steps which consist in heating phosphorus oxychloride to a reaction temperature with approximately three molecular equivalents of meta-xenol.

9. In a method of making meta-xenyl-diphenyl phosphate, the step which consists in heating meta-xenyl phosphoric acid dichloride to a reaction temperature with approximately two molecular equivalents of phenol.

10. In a method of making mcta-xenyl-di- (ortho-cresyl) phosphate, the step which consists in heating meta-acnyl phosphoric acid (liehloride to a reaction temperature with approximately two molecular equivalents of ortho-cresol.

ii. A liquid or low-melting organo-derivative of phosphoric acid having the general formula:

wherein Y and Z each represent a member of the group consisting of halogen and aryloxy groups. 12. A triaryl phosphate compound having the general formula:

wherein R and R represent aromatic hydrocarbon radicals.

13. Tri-meta-xenyl phosphate. 14. Meta-xenyl-di-phenyl phosphate. 15. Meta xenyl-ditortho-cresyl) phosphate,

EDGAR C. BRITTON. SHAILER. L. BASS. 

